Method of forming articles

ABSTRACT

An improved method of forming an article includes providing continuous, woven, flat, helical tape of filaments and a continuous flat, helical tape of foil. The two helical tapes are interleaved to form a helical assembly having turns of filaments alternating with turns of foil. Deformation forces are applied against the turns of the helical assembly in a direction parallel to the central axis of the helix to bond the turns of the tapes off oil and filament together while maintaining the filaments free of axially extending forces. During the bonding of the turns of the helical foil and filament tapes, the tapes may be bonded to a housing or other component of an article to be reinforced. Radial reinforcing can be provided by including in the helical assembly a layer having filaments with central axes which are radial relative to the central axes of the filaments of the helical tape.

BACKGROUND OF THE INVENTION

The present invention relates to a new and improved method of forming afilamentary reinforced article and articles formed thereby.

During the forming of filamentary reinforced articles, the reinforcingfilaments tend to crack and/or buckle if they are subjected to tensionor compression forces along the filament axis during a pressingoperation. In order to avoid cracking and/or buckling of the filaments,a filamentary reinforced article may be formed in the manner disclosedin U.S. patent application Ser. No. 879,366 filed June 27, 1986 byGordon S. Doble and entitled "Method of Forming Articles".

The patent application identified above discloses forming a filamentaryreinforced article by winding a composite preform and a carrier striparound an axis to form a layered preform. The layers of the preform arethen bonded together and densified by applying pressure forces in adirection generally parallel to the axis around which the layers of thepreform were wound. The layers of the preform are bonded together andthe density of the preform is increased without subjecting thereinforcing filaments to excessive tension or compression forces in adirection along the filaments.

SUMMARY OF THE INVENTION

The present invention provides a method of forming a filamentaryreinforced article from a helical tape of filaments and a helical tapeof metallic foil. The helical tape of filaments and the helical tape offoil are interleaved to form a helical assembly having alternate turnsof filaments interspersed with turns of foil. Deformation forces areapplied against the turns of the helical assembly in a directionparallel to the central axis of the helical assembly. These deformationforces bond the metal of the helical tape of foil to the filaments ofthe helical tape of filaments while maintaining the filamentssubstantially free of forces extending along the filament axis thatcould cause plastic deformation thereof such as cracking or buckling.

As the helical tape of filaments and the helical tape of foil are bondedtogether, they may also be bonded to a member which they are toreinforce. If desired, radial reinforcing can be provided between theturns of the double helix.

Accordingly, it is the object of this invention to provide a new andimproved method of forming an article by interleaving helical filamentsand foil and then applying force to consolidate and bond the turns ofthe helical filaments and foil together while maintaining the filamentsfree of plastic deformation forces extending along the axes of thefilaments.

The present invention also provides a composite filament reinforcedarticle comprising a consolidated metallic matrix and a plurality ofrelatively low ductility, high strength filaments extending helicallythrough the matrix and diffusion bonded therein with the filaments beingcontinuous from end to end and substantially free of plastic deformationevidenced by cracks or buckling along their length. For gas turbinedisks or rings, the axis of the helix (helically extending filaments) issubstantially coincident with the axis of rotation of the disk or ring.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and features of the present inventionwill become more apparent upon consideration of the followingdescription taken in connection with the accompanying drawings wherein:

FIG. 1 is a partially broken away pictorial illustration of afilamentary article constructed in accordance with the method of thepresent invention.

FIG. 2 is an illustration of a helical tape of filaments.

FIG. 3 is a sectional view, taken generally along the line 3--3 of FIG.2, illustrating how helical filaments in the tape of FIG. 2 areinterconnected.

FIG. 4 is an illustration of a helical tape of foil.

FIG. 5 is a sectional view, taken generally along the line 5--5 of FIG.4, illustrating the construction of the helical tape of foil.

FIG. 6 is an illustration of a helical assembly formed by interleavingthe helical tapes of FIGS. 2 and 4.

FIG. 7 is an enlarged fragmentary sectional illustration depicting thehelical assembly of FIG. 6 in a closed condition with the turns of thehelical assembly adjacent to each other.

FIG. 8 is a schematic illustration depicting the closed helical assemblyof FIG. 7 in a die.

FIG. 9 is an enlarged fragmentary sectional illustration, similar toFIG. 7, of a portion of the article of FIG. 1 formed by bonding theturns of the helical assembly of FIG. 6 together.

FIG. 10 is a schematic illustration, generally similar to FIG. 9,illustrating the closed helical assembly in a circular opening in amember to which it is to be bonded.

FIG. 11 is a schematic sectional view, generally similar to FIG. 10,illustrating the closed helical assembly in a cylindrical opening in amember to which it is to be bonded and illustrating a second memberwhich is to be bonded to the helical assembly.

FIG. 12 is a plan view illustrating how arcuate segments are cut from aflat sheet of foil to form the helical tape of foil of FIG. 4.

FIG. 13 is a schematic illustrating depicting the manner in which ahelical tape of foil is cut from a tubular metal member.

FIG. 14 is an illustration of a portion of a helical assembly having aradial reinforcing layer.

FIG. 15 is an enlarged fragmentary plan view of a portion of a helicaltape of filaments used in the helical assembly of FIG. 14.

FIG. 16 is a fragmentary plan view illustrating the orientation offilaments in the reinforcing layer of FIG. 14.

DESCRIPTION OF SPECIFIC PREFERRED EMBODIMENTS OF THE INVENTION

An annular cylindrical filamentary reinforced article 10 is illustratedin FIG. 1. The article 10 is representative of numerous differentarticles of circular and noncircular cross-sectional configurationswhich can be made by the method of the present invention. The articlesmade using the method of the present invention can be used in manydifferent environments. However, it is contemplated that the article 10will be used as a reinforcing element for components of an aircraft andaerospace structure. For example, the article 10 could be a reinforcingelement for a component which is rotated at high speeds during operationof a gas turbine engine such as a disk or ring on which compressor orturbine blades can be mounted.

The illustrated article 10 is an annular cylindrical ring having acentral axis 12 which extends through a cylindrical central opening 14in the ring. The ring has a pair of parallel circular side surfaces 16and 18. The side surfaces 16 and 18 are interconnected by a cylindricalradially outer side surface 20 and a cylindrical inner side surface 22.

The article 10 is a consolidated one-piece structure formed of helicalreinforcing mono-filaments 26 which are bonded together by and disposedin a metal matrix 28. The reinforcing filaments 26 can be of any one ofmany known compositions, such as boron, coated boron, silicon carbide,refractory metal, or ceramic. The filaments may also be yarns ofmaterials such as graphite, alumina, or other ceramics. Also useful inthe process are filaments already enveloped by a matrix or layer such asan infiltrated graphite aluminum wire preform. For such enveloped orcoated preforms, the assembly of FIG. 6 would not necessarily employfoil as a matrix. The specific manner in which the filaments 26 are madeand the specific composition of the filaments does not, per se, form apart of the present invention. However, the filaments 26 are relativelyhigh strength, generally have limited or low ductility compared to themetal matrix, and reinforce the metal matrix 28 to enable the article 10to withstand very high centrifugal forces under severe operatingconditions.

Although the article 10 has been shown in FIG. 1 as being a cylindricalring with rotational symmetry and with an open center, the article 10could be a solid circular disk, that is a disk which does not have anopening in the center. In addition, the article 10 could have aconfiguration other than the illustrated circular configuration. Forexample, it is contemplated that the article 10 could be formed with anelliptical, a generally rectangular or even a nonsymmetricalconfiguration if desired. Of course, the specific configuration of thearticle 10 will depend on the environment in which the article 10 is tobe used.

In order to form the article 10, a continuous, woven, flat-surfacedhelical tape 32 (FIG. 2) of mono-filaments is provided. The helicalfilaments 26 are held in a side-by-side relationship at the desiredradius and woven together by strands 33 of weaving thread ribbon, orwire (FIG. 3). The strands 33 of wire hold the filaments in a collimated(aligned) relationship with lateral spaces or voids 27 between thefilaments and with the central axes of each of the filaments 26 disposedon a radius of the helix. Each turn of the helical tape 32 has the sameinside and outside diameter. Each of the helical filaments 26 extendsfrom a lower end 34 to the upper end 35 of the tape 32. Such a helicaltape of mono-filaments has been obtained from Woven Stuctures, Inc.,Compton, California.

In order to provide material for the metal matrix 28, a helical tape ofmetallic foil 38 (FIG. 3) is provided. The metallic tape that ultimatelyprovides a metallic matrix may comprise metals and alloys of varioustypes; e.g., titanium, titanium alloys and nickel, iron, or cobalt-basedsuperalloys as well as others. The helical tape 38 of foil has insideand outside diameters which are the same as the inside and outsidediameters of the helical tape 32 of filaments. However, the helical tape38 of foil has one more turn than the helical tape 32 of filaments. Thehelical tape of foil is a continuous flate, soild tape with arectangular cross sectional configuration (FIG. 4).

The helical tape 32 of filaments and the helical tape of foil areinterleaved to form an interleaved helical assembly 42 (FIG. 6). Thus,upwardly facing major side surface 44 of the helical tape 38 foil isplaced adjacent to a downwardly facing major side surface 46 of thehelical tape 32 of filaments. Similarly, an upwardly facing major sidesurface 48 of the helical tape of filaments is placed adjacent to adownwardly facing major side surface 50 of the helical tape 38 of foil.

The turns of the helical tape 32 of filaments and the helical tape 38 offoil are aligned with each other so that the central axis 54 (FIG. 2) ofthe helical tape 32 of mono-filaments is coincident with a central axis56 (FIG. 4) of foil. This results in the helical assembly 42 (FIG. 6)having a central axis 58 which is the common central axis for thehelical tape 32 of filaments and the helical tape 38 of foil. Thehelical assembly 42 has the same inside and outside diameter throughoutits axiel extent.

The space between the interleaved turns of the helical tape 32 offilaments and the helical tape 38 of foil are compressed or closed sothat the major side surfaces 44 and 50 of the helical tape of foil abutthe major side surfaces 46 and 48 of the helical tape 32 of filaments inthe manner illustrated in the enlarged sectional view of FIG. 7. Whenthe closed helical assembly 42 is viewed in a radial cross section, asshown in FIG. 7, the turns of the helical tape 32 of filaments 26 form aplurality of layers 62 of filaments 26 with lateral voids 27therebetween disposed between a plurality of layers 64 of foil. Thehelical tape 38 of foil has one more complete turn than the helical tape32 of filaments. Therefore, a layer 64 of foil is provided beneath thelower turn of the helical tape 32 of filaments and above the upper turnof the helical tape of filaments. In FIG. 6, the turn of foil layer 64is broken at ends 38a for convenience; actually, foil layer 64 extendsuninterrupted between broken ends 38a.

Although the filaments 26 are shown in cross section in FIG. 7, each ofthe filaments 26 extends from the beginning to the end of the helicaltape 32 of filaments. Therefore, there are no joints in the filaments26. Since each of the helical filaments 26 is free of joints, thehelical filaments do not have any areas which are weaker than otherareas of the filaments.

The helical filaments 26 are held in a spaced apart collimatedrelationship by the strands 33 of weaving material (FIG. 3). Therefore,the helical assembly 42 forms an annular article preform 68 (FIG. 7)which is not fully dense. In addition, the layers 62 and 64 of thearticle preform 68 are not interconnected. The article preform 68 has anannular configuration with inside and outside diameters which are thesame as the inside and outside diameters of the helical tapes 32 and 38of filaments and foil. In the illustrated embodiment of the invention,the preform 68 has a rectangular cross sectional configuration.

In order to obtain a fully dense article 10, it is necessry that thepreform 68 be consolidated or compacted. In order to maximize thestrength and the operating characteristics of the article 10, it isnecessary to bond and consolidate the layers 62 and 64 of the preform 68by filling voids 27 and bonding the mono-filaments in the matrix formedby the foil to form a unitary structure. However, during the compactingand bonding of the preform 68, it is imperative that the reinforcingfilaments 26 are not cracked under the influence of tension forces orbuckled under the influence of compression forces acting in thedirection of the filament axis, that is in a direction parallel to alongitudinal central axis of a filament. Thus, the filaments 26 can besubjected to elastic forces along the filament of a magnitude largeenough to cause only elastic deformation of the filaments. The filaments26 are maintained free of forces along the filament of a magnitudesufficient to cause plastic deformation or fracture of the filaments.

Bonding and compaction of the article preform 68 are effected toincrease the density of the article preform and form a unitary article10 (FIG. 1). To this end, the entire preform 68 is enclosed in anannular opening 74 in a die 76. The annular opening 74 has a generallyrectangular cross sectional configuration and is of substantially thesame size as the preform 68. An annular punch 78 is sized to fit intothe annular opening 74 and is used to apply pressure against the articlepreform 68 in the manner indicated by the arrow 80 in FIG. 8.

Before pressure is applied against the article preform 68 by the punch78, the preform 68, die 76 and punch 78 are heated to a relatively hightemperature sufficient to promote diffusion bonding of the components ofthe preform. Once this has been down, the punch 78 is pressed firmlydownwardly against the preform 68. This results in the application offorce against the major side surfaces of the helical tapes 32 and 38 offilaments and foil. The force against the preform 68 reduces distancesbetween the layers 62 of filaments and causes the metal of the foil tape38 to plastically flow into the lateral voids or spaces 27 between thefilaments 26.

The die 76 restrains the preform 68 against radial expansion andcontraction. Therefore, the filaments 26 are maintained free of plasticdeformation forces extending axially along the filaments. This preventsthe filaments from being cracked or buckled under the influence ofaxially extending forces along the filaments.

The force applied by the punch 78 in an axial direction to the annularpreform 68 results in the material of the helical foil tape 38 flowingunder plastic deformation forces into the lateral spaces 27 between thefilaments 26 to form a fully dense article. Due to the relatively hightemperature to which the preform 68 is heated and the pressure appliedagainst the preform by the punch 78, the material of the helical tape 38of foil is firmly bonded to the filaments 26 with a solid statediffusion bonding process. As this is occurring, the reinforcingfilaments 26 do not undergo appreciable plastic flow.

The process may also be used for partial liquid phase bonding in asimilar manner. The temperature in partial liquid phase bonding is justabove the solidus temperature of the matrix alloy producing a materialwhich contains a small amount of liquid phase plus solid phase duringbonding; a so-called "mush consistency". Bonding is performed by heatingpreform 68 above the solidus temperature, bonding with a pressure muchlower than required for solid state diffusion bonding, and cooling downbelow the solidus to complete the process.

The direction of deformation of the preform 68 in the die 76 is in anaxial direction indicated by the arrow 80 in FIG. 8. Therefore, thepreform 68 is compacted in a direction parallel to the central axis 58of the helical assembly 42 (FIG. 6) with the helical mono-filamentscompressed in the axial direction. This prevents radial buckling orcracking of the reinforcing filaments 26.

The extend of axial compression of the annular article preform 68 isequal to the volume of metal which must be displaced from the helicaltape 38 of foil into the spaces 27 between the filaments 26 of thehelical tape 32 of filaments. The force applied by the punch 78 againstthe article preform 68 causes the material of the layers 64 of foil tobecome interspersed with the filaments 26 in the layer 62 of filamentsto thereby result in a decrease in the axial extent of the articlepreform. The filaments 26 are not stressed plastically in axial tensionor compression in a direction along the filaments. Therefore, there isno tendency for the filaments to break or to buckle.

The resulting article 10 has a fully dense metal matrix 28 (FIG. 9) inwhich the helical reinforcing filaments 26 axially compressed aredisposed and diffusion bonded in the matrix. Each of the reinforcingfilaments 26 is continuous throughout the axial extend of the article10. Thus, each helical filament extends from one axial end of thearticle 10 through a plurality of turns in a central portion of thearticle to the opposite axial end of the article with the axis of thehelix substantially coincident with the rotational axis of the article10. Since the filaments 26 are free of joints, they provide a verystrong reinforcing for the article. The pressure applied during bondingis preferably controlled each that the filaments 26 retain a helicalorientation, albeit axially compressed, by virtue of the matrix foilbeing consolidated around the filaments.

Once the article has been formed by a hot pressing operation in themanner previously described, the punch 78 is withdrawn and the articleis removed from the die 76. To facilitate removal of the article fromthe die 76, the die is advantageously made incorporating an ejectionmechanism consisting of circumferentially spaced apart ejection pins 75and an annular ajector plate 77 or similar mechanisms which are widelyused. Pins 75 can be actuated by suitable mechanical, hydraulic or othermechanisms to move ejector plate 77 upwardly in FIG. 8 to eject thearticle 10.

After the preform 68 has been bonded and densified to form the article10 and the article has cooled, the annular article has inside andoutside diameters which are substantially the same as the inside andoutside diameters of the helical tapes 32 and 38. The fully densearticle 10 can be used to reinforce many different types of componets ofvarious types of machines. The article could be mounted in an openingformed in the component and held in place by a suitable mechanicalconnection. Alternately, the article could be bonded into a componentusing a secondary operation such as vacuum hot press diffusion bondingor hot isostatic pressing.

It is contemplated that it may be desirable to bond the annularreinforcing article 10 directly to the component which is to bereinforced rather than having the reinforcing ring be separate from thecomponent or employing a two-step fabrication process. In the embodimentof the invention illustrated in FIG. 10, the reinforcing article 10 isbonded directly to a component which is to be reinforced. Since theembodiment illustrated in FIG. 10 is generally similar to the embodimentof the invention illustrated in FIGS. 1 through 9 similar numerals willbe used to designate similar components, the suffix letter "a" beingadded to FIG. 10 to avoid confusion.

In the embodiment of the invention illustrated in FIG. 10, a circularhousing 84 forming a part of an article to be reinforced with theannular ring 10 is positioned in a circular opening 86 in a die 76a. Thehousing section 84 has an upwardly facing annular opening 74a which issized to receive the article preform 68a. After the die 76a, housingsection 84 and a punch 78a have been heated to a temperature sufficientto promote diffusion bonding of the metal of the article preform 68a,the punch is pressed against the preform 68a to cause a plastic flow ofthe metal of the helical tape of foil between the filaments of thehelical tape of filaments.

The housing section 84 may be made of the same or different metal as thehelical tape of foil. The housing section 84 has been heated to atemperature sufficient to promote diffusion bonding of the metal of thehelical tape of foil to the housing 84. Therefore, during densificationand bonding of the metal of the preform 68a, the metal of the foilbecomes bonded to the housing section 84.

In the embodiment of the invention described in connection with FIG. 10,the punch 78a is removed from the opening 74a in the housing section 84leaving the reinforcing ring exposed. The opening may be closed bybonding an insert during a secondary operation. However, it iscontemplated that it may be desirable to close the opening 74a in thehousing 84 with a single operation. In the embodiment of the inventionillustraded in FIG. 11, the opening in the housing section is closedduring consolidation. Since the embodiment of the invention illustratedin FIG. 11 is generally similar to the embodiment of the inventionillustrated in FIG. 10, similar numerals will be utilized to describesimilar components, the suffix letter "b" being associated with thenumerals of FIG. 11 to avoid confusion.

A preform 68b, formed by interleaving a helical tape of filament and ahelical tape of foil to form a helical assembly, is positioned in anannular opening 74b in the housing section 84b. The housing section 84bis located in an opening 86b formed in a die 76b. An annular housingring 90 is provided to close and remain part of the annular opening 74bin the housing section 84b.

Once the preform 68b, die 76b, housing section 84b and closure ring 90have been heated to a temperature sufficient to promote diffusionbonding of the material of the helical tape of foil to the filaments inthe helical tape of filaments and to the housing section 84b and theclosure ring 90, a force, indicated by the arrow 80b is applied againsta punch 78b to press the closure ring 90 against the preform 68b. Asthis occurs, the metal tape of foil is diffusion bonded to the housingsection 84b and to the closure ring 90. In addition, the metal of thepreform 68b is diffusion bonded with filaments in the helical tape offilaments to form a fully dense reinforcing ring.

The helical tape 38 of foil can be formed in many different ways. Thus,a strip 94 (FIG. 12) of foil could be cut into arcutate segments 96. Thearcuate strips 96 would then be interconnected to form the continuoushelical tape 38 of foil.

The connecting of the arcuate strips 96 of foil can be eliminated byforming the helical tape 38 of foil from a continuous winding 98 (FIG.13) cut from a tubular member 100. The continuous winding 98 has insideand outside diameters which are the same as the inside and outsidediameters of the helical tape 38 of foil. Of course, the helical tape 38of foil could be formed in other ways if desired.

When the article 10 is used in certain environments, the article may besubject to radial loads. In the embodiment of the invention shown inFIGS. 14-16, radial reinforcement is provided for the article. Since theembodiment of the invention shown in FIGS. 14-16 is generally similar tothe embodiment of the invention shown in FIGS. 1-9 similar numerals willbe utilized to designated similar components, the suffix letter "c"being associated with the embodiment of FIGS. 14-16 to avoid confusion.

A helical assembly 42c is formed by a helical tape 32c of filaments anda helical tape 38c of foil. The helical assembly 42c is provided withone or more layers of radial reinforcement, indicated at 104 in FIG. 14.The radial reinforcement 104 includes a circular layer 106 of filamentsand a circular layer 108 of tape. The layer 106 is a flat, woven tape ofthe same size as one complete turn of the helical tape 32c of filaments.The layer 108 is a flat foil tape of the same size as the layer 106 andone complete turn of the helical tape 38c of foil. Although the layers106 and 108 of filaments and tape have been shown as having a lengthequal to only one turn of the helical tapes 32c and 38c of filaments andfoil, the layers 106 and 108 could be longer if desired.

The layer 106 of filaments includes a plurality of radially extendingfilaments 112 (FIG. 16) which extend between a circular inside edge 116and a circular outside edge 118 in the annular layer 106 of reinforcingtape. Thus, the filaments 112 have a length which corresponds to theradial width of the reinfocing tape 106. The filaments 112 are disposedon radii of the circular layer 106. Therefore, the ends of the filaments112 are closer together at the inner edge 116 of the layer 106 than atthe outer edge 118. If desired, the filaments 112 could be skewed at anacute angle to the radial orientation shown in FIG. 16 or alternated ina plus and minus configuration.

The reinforcing tape 108 of foil has an inside diameter and outsidediameter which is the same as the inside and outside diameter of theradial reinforcing tape or layer 106 of filaments. The length of thereinforcing tape 108 of foil is the same as the length of thereinforcing tape 106 of filaments. The lower major side surface of thereinforcing tape of foil 108 is disposed in abutting engagement with anupper major side surface 48c of the helical tape 32c of filaments 26c(FIG. 15). The lower major side surface of the radial reinforcing tape106 is disposed in abutting engagement with the upper side surface 44c(FIG. 14) of the foil tape 108. Although the helical tape 32c offilaments has been shown in FIG. 14 as being at the upper end of thehelical assembly 42c, it is contemplated that the helical tape 38c offoil will extend upwardly and over last turn of the helical tape 32c offilaments.

Since the filaments 112 in the radial reinforcing tape 106 extendradially (FIG. 16), the filaments 112 are effective to reinforce anarticle, similar to the article 10, against radial loads. Thus, thefilaments 26c (FIG. 15) in the helical tape 32c of filaments extendthroughout the length of the tape and have a helical configuration. Thefilaments 112 in the radial reinforcing tape 106 (FIG. 16) extendbetween opposite longitudinally extending edge portions 116 and 118 ofthe radial reinforcing tape and have a short, linear configuration. Thefilaments 112 are interconnected by strands 120 of weaving thread orwire.

Upon compaction of an article preform which includes the radialreinforcing tapes 106 and 108, the metal of the tape 108 flows into theradially extending spaces between the filaments 112 of the tape 106 andbecomes bonded to the filaments to form a fully dense portion of thearticle. If desired, the radial reinforcing tapes 106 and 108 could beprovided at several axially spaced apart locations along the helicalassembly 42c. In addition, it is contemplated that the radialreinforcing tapes 106 and 108 could have a length which is greater thana single turn of the helical assembly 42c. Of course, the length of theradial reinforcing tapes 106 and 108 and the number of radialreinforcing tapes provided in the helical assembly 42c will depend uponthe particular environment in which the resulting articles is to beused.

The method of the present invention can be used to make articles havingmany different configurations and having many different types of helicalreinforcing filaments 26 disposed in matrices 28 of many different typesof metal. However, one specific example of an article 10 which might beconstructed in accordance with the present invention could have aplurality of helical boron reinforcing individual mono-filaments 26disposed in a titanium-6 aluminum-4 vanadium metal matrix 28. Thisarticle is enclosed by a housing 84b of the same metal as the matrix,that is titanium-6 aluminum-4 vanadium.

In order to make this specific article, a helical tape 32 is formed of aboron polar fabric having a 2--2 twill weave construction. The helicalboron mono-filaments 26 have a diameter of 0.0056 of an inch and aredisposed with a spacing of 100 filaments per inch, that is a one inchwidth of the helical tape of filaments would contain 100 helicalfilaments 26 arranged in a side-by-side relationship. In this specificexample, the helical tape 32 of filaments has a width of three quartersof an inch. This specific helical tape 32 has a nine inch outsidediameter and a seven and a half inch inside diameter. The helical tape32 of filaments extend for five complete turns. The filaments areinterconnected by a copper wire weaving strand 33 having a diameter of0.003 of an inch with fifteen strands per inch.

In this specific exmple, the helical tape 34 of foil has a thickness of0.006 of an inch and a width of three quarters of an inch. The helicaltape of foil has six turns. Therefore, a helical assembly 42 of thehelical tape 32 of boron filaments and the helical tape 34 of foil has alayer of the foil tape at both ends of the helical assembly.

After the helical tape 32 of boron filaments and the helical titanium-6aluminum-4 vandadium foil tape 38 of the present example have beeninterleaved to form a helix assembly 42, the helical assembly whichforms a specific article preform 68 can be consolidated at sufficienttemperature and pressure in the apparatus of FIG. 8 for a timesufficient to cause a bonding of metal of the helical tape 38 of foil tothe boron filaments in the helical tape 32 of filaments and theformation of a fully dense consolidated reinforcing ring 10.

The present invention provides a method of forming a filamentaryreinforced article 10 from a helical tape 32 of filaments and a helicaltape 38 of foil. The helical tape 32 of filaments and the helical tape38 of foil are interleaved to form a helical assembly 42 having turns offilaments interspersed with turns of foil. Deformation forces 80 areapplied agaisnt the turns of helical assembly 42 in a direction parallelto the central axis 58 of the helical assembly. These formation forcesbond the metal of the helical tape 38 of foil to the filaments 26 of thehelical tape 32 of filaments while maintaining the filamentssubstantially free of plastic deformation forces extending axially alongthe filaments.

As the helical tape 32 of filaments and the helical tape 38 of foil arebonded together, they may also be bonded to a member 84 which they areto reinforce. If desired, radially reinforcing 104 can be providedbetween the turns of the helical assembly.

While certain preferred embodiments of the invention have been describedabove, those familar with the art will recognize that variousmodifications and changes can be made therein for practicing theinvention as defined by the following claims:

I claim:
 1. A method of forming an article comprising the steps ofproviding a helical tape of filaments, providing a helical tape of metalfoil, interleaving the helical tape of filaments and the helical tape ofmetal foil to form a helical assembly having turns of filamentsinterspersed with turns of metal foil, applying deformation forceagainst the turns of the helical assembly in a direction parallel to thecentral axis of the helical assembly and bonding the turns of thehelical tape of metal foil to the turns of the helical tape of filamentswhile maintaining the filaments substantially free of plasticdeformation forces extending axially along the filaments.
 2. A method asset forth in claim 1 wherein said step of bonding the turns of thehelical tape of metal foil to the turns of the helical tape of filamentsinclude plastically deforming the turns of the tape of foil to form aone-piece circular metal matrix holding helical turns of filaments.
 3. Amethod as set forth in claim 1 wherein said step of bonding the turns ofthe helical tape of foil to the turns of the helical tape of metalfilaments includes decreasing the distance between turns of the helicaltape of filaments.
 4. A method as set forth in claim 1 wherein said stepof providing a helical tape of filaments includes providing a flat woventape of helical filaments interconnected by strands extendingtransversely to the filaments.
 5. A method as set forth in claim 4wherein said step of bonding the helical tape of metal foil to thehelical tape of filaments includes plastically deforming the metal ofthe tape of foil to fill spaces between the helical filaments of thetape of filaments.
 6. A method as set forth in claim 1 further includingthe step of providing a member having a circular opening, positioningthe helical assembly in the circular opening in said member andthereafter, performing said steps of bonding the turns of helical tapeof metal foil to the turns of the helical tape of filaments.
 7. A methodas set forth in claim 6 further including the step of bonding the turnsof the helical tape of metal foil and the turns of the helical tape offilaments to said member while preforming said step of bonding the turnsof the helical tape of metal foil and the helical tape of filaments. 8.A method as set forth in claim 1 wherein said step of providing ahelical tape of filaments includes providing a tape in which each of thefilaments extends throughout the length of the helical tape.
 9. A methodas set forth in claim 1 further including the step of providing a layerof filaments between the turns of the helical assembly with the centralaxis of the filaments of the layer of filaments extending transverselyto the central axis to the filaments of the helical tape of filaments.10. A method of forming an article, said method comprising the steps ofproviding a helical series of filaments disposed in a side-by-siderelationship along a radius of the helical series of filaments and witheach filament extending between axially opposite ends of the helicalseries of filaments, positioning metal foil between adjacent turns ofthe helical series of filaments, applying deformation forces against theturns of the helical series of filaments in a direction parallel to thecentral axis of the helical series of filaments, and bonding the metalfoil to the helical series of filaments while maintaining the filamentssubstantially free of plastic deformation forces extending axially alongthe filaments.
 11. A method as set forth in claim 10 further includingpositioning other filaments adjacent the helical series of filamentswith said other filaments extending transversely to the filaments in thehelical series of filaments.
 12. A method as set forth in claim 10further including positioning a layer of filaments between turns of thehelical series of filaments with the filaments in the layer of filamentsin a radially extending orientation relative to the central axis of thehelical series of filaments.
 13. A method as set forth in claim 10wherein said step of positioning metal foil between the adjacent turnsof the helical series of filaments includes interleaving a helical tapeof metal foil with the helical series of filaments to form a helicalassembly.
 14. A method as set forth in claim 10 wherein said step ofbonding the metal foil to the helical series of filaments includesplastically deforming the metal of the foil into spaces between adjacentfilaments.
 15. A method of forming an article comprising the steps offorming a helix having helical turns of mtallic matrix materialinterspersed with helical turns of side-by-side filaments havingrelatively high strength and low ductility compared to the metallicmatrix material, applying a deformation force against the turns of thehelix in a direction parallel to the central axis of the helix andbonding the turns of the metallic matrix material and turns of thefilaments while maintaining the relatively high strength, low ductilityfilaments substantially free of plastic deformation forces extendingaxially along the filaments.